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Cogl 2.0 Reference Manual | ![]() |
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Top | Description |
Rectangle textures (non-normalized coordinates)Rectangle textures (non-normalized coordinates) — Functions for creating and manipulating rectangle textures for use with non-normalized coordinates. |
CoglTextureRectangle; CoglTextureRectangle * cogl_texture_rectangle_new_with_size (CoglContext *ctx
,int width
,int height
,CoglPixelFormat internal_format
,CoglError **error
); CoglTextureRectangle * cogl_texture_rectangle_new_from_bitmap (CoglBitmap *bitmap
,CoglPixelFormat internal_format
,CoglError **error
); CoglBool cogl_is_texture_rectangle (void *object
);
These functions allow low-level "rectangle" textures to be allocated.
These textures are never constrained to power-of-two sizes but they
also don't support having a mipmap and can only be wrapped with
COGL_PIPELINE_WRAP_MODE_CLAMP_TO_EDGE
.
The most notable difference between rectangle textures and 2D textures is that rectangle textures are sampled using un-normalized texture coordinates, so instead of using coordinates (0,0) and (1,1) to map to the top-left and bottom right corners of the texture you would instead use (0,0) and (width,height).
The use of non-normalized coordinates can be particularly convenient when writing glsl shaders that use a texture as a lookup table since you don't need to upload separate uniforms to map normalized coordinates to texels.
If you want to sample from a rectangle texture from GLSL you should use the sampler2DRect sampler type.
Applications wanting to use CoglTextureRectangle should first check
for the COGL_FEATURE_ID_TEXTURE_RECTANGLE
feature using
cogl_has_feature()
.
CoglTextureRectangle * cogl_texture_rectangle_new_with_size (CoglContext *ctx
,int width
,int height
,CoglPixelFormat internal_format
,CoglError **error
);
Allocates a new CoglTextureRectangle texture with a given width
, height
and internal_format
. This texture is a low-level texture that
the GPU can sample from directly unlike high-level textures such
as CoglTexture2DSliced and CoglAtlasTexture.
width
, height
) where width
and height
are the width and height of the texture.
COGL_FEATURE_ID_TEXTURE_RECTANGLE
feature
using cogl_has_feature()
.
|
A CoglContext pointer |
|
The texture width to allocate |
|
The texture height to allocate |
|
The desired internal texture format |
|
An optional CoglError pointer for reporting exceptions |
Returns : |
A pointer to a newly allocated
CoglTextureRectangle texture or if the size was too large
or there wasn't enough memory NULL is returned and error
set. [transfer full]
|
Since 1.10
Stability Level: Unstable
CoglTextureRectangle * cogl_texture_rectangle_new_from_bitmap (CoglBitmap *bitmap
,CoglPixelFormat internal_format
,CoglError **error
);
Allocates a new CoglTextureRectangle texture which will be
initialized with the pixel data from bitmap
. Internally the data
will be stored in the format given by internal_format
. This
texture is a low-level texture that the GPU can sample from
directly unlike high-level textures such as CoglTexture2DSliced
and CoglAtlasTexture.
width
, height
) where width
and height
are the width and height of the texture.
COGL_FEATURE_ID_TEXTURE_RECTANGLE
feature
using cogl_has_feature()
.
|
A CoglBitmap |
|
the CoglPixelFormat to use for the GPU storage of the texture |
|
A return location for a CoglError or NULL
|
Returns : |
A pointer to a newly allocated
CoglTextureRectangle texture or if the size was too large
or there wasn't enough memory NULL is returned and error
set. [transfer full]
|
Since 2.0
Stability Level: Unstable
CoglBool cogl_is_texture_rectangle (void *object
);
Gets whether the given object references an existing CoglTextureRectangle object.
|
A CoglObject |
Returns : |
TRUE if the object references a
CoglTextureRectangle, FALSE otherwise. |